Welding apparatus



sept 12,1944, n I

wELDxNG APPARATUS Filed Nov. 4. 1940 j i sheets-Sheet. 1

V Ivento: Jamesl". Cat, lett,

HsAttoney Sept. 3?., 1944.

J. T. CATLETT WELDING APPARATUS Filed Nov. 4, 1940 4 Sheets-Sheet 2Inventor. mes-I. Catlett,

' His Attorney.

sept. 12, 1944; 11C/LETT 2,358,144

A """WELDING APPARATUS Filed NOV. 4, 1940 4 Sheets-Sheet 3 ITM/erfat;James "ICatlett,

HIS Attcrwey.

5Pf 12 1944- y J. T. cATLE-r 2,358,144

y WELDING APPARATUS Filed NOV. 4, 1940 4'SheetS-Sheet 4 /a Fsglo. ,3

73 I 'alie j 74 4 Invetcr: Jam @5T Catl ett,

l-IIS Attorney Patented Sept. 12, 1944 WELDING APPARATUS James T.Catlett, Scotia, N. Y., asslgnor to (leneral Electric Company, acorporation of New York Application November 4', 1940, serial No.364,168

12 claims. (c1. 113-59) My invention relates to fusion welding apparatusparticularly suited for joining work assemblies along inner and outerconcentric arcuate seams. Certain aspects of my invention are, however,of more general application in that they relate to apparatus forcontrolling weld penetration and particularly notch-back at the end of afusion weld. This notch-back control is accomplished by conducting heatfrom the seam at the ends thereof in progressively increasing amountssuicient to taper off weld penetration at the ends of the seam, where ifthis penetration is not thus decreased, the molten metal in the seamruns back from the end of the seam forming a ball of metal which resultsin a decided notch at the end of the seam.

The machine illustrated in the drawings is particularly suited forwelding magazine cases for Bren machine guns. The nature of these casesis fully illustrated and descri-bed in an article in Machinery (London)for July 21, 1938, pages 481 to 484. These magazine cases have also beenillustrated in applicants drawings.

These cases are formed from two stampings which when assembled presentfor welding inner and outer arcuate concentric seams which extend alongthe inner and outer edges of the cases which are segmental in shape.

It is an object of my invention to provide a welding machine in whichthe inner and outer concentric arcuate seams of a work assembly aretraversed relatively to a welding agency which is properly positionedover the assembly so that both its seams may be welded by onepositioning of the work assembly in the machine.-

It is a further object of my invention to provide a work holding jig andoiset segmental clamp in which said jig is properly located so thatrotation of the clamp traverses inner and outer arcuate work seamsrelative to a single welding agency which may be properly positioned forwelding either of these seams depending upon the arc of travel ofthework clamp and jig supported therein.

Another object of my invention is to provide apparatus for fusionwelding seams whereby notch-back at their ends is prevented.

Further objects and advantages of my invention will become apparent fromthe following description of the embodiment thereof illustrated in theaccompanying drawings.

In these drawings Fig. 1 is a front view of a welding machine embodyingmy invention; Figs. 2 and 3 are side and plan views of the work clampand jig with portions broken away to illustrate the constructionsthereof; Fig. 4 is a side view in which a section of the work clampingmembers and jig has been taken along line 4-4 of Fig. 2; Fig. 5 is aside view showing two magazine cases supported on a mandrel forming partof the jig; Fig. 6 i's an enlarged view of one end of the :lig showingthe construction thereof whereby notch-back at the end of a seam isprevented; Fig. 'I is a side sectional view of the support for thewelding agency by means of which it is located in either of two weldingpositions or moved a substantial distance away from the Aworlr clamp tofacilitate loading and unloading thereof; Fig. 8 is a sectional view ofthissame supp ort along line 8-8 of Fig. 7; Fig. 9 isanother sectionalview of this same support along line 9 9 of Fig. 7; Fig. 10 is asectional view of the supporting axle for the work clamp illustratingthe passages therethrough for pressure iiuid, its manner of support andthe location thereon of a counterbalance for the work clamp; Fig. 11 isa diagram illustrating the manner in which uid under pressure issupplied to the work clamp for cooling the clamping members thereof andto the fluid operated mechanism by means of which its clamping membersare moved toward and away from one another, and Fig. 12 is a side viewof the counterbalance above referred to.

Themachine illustrated in Fig. 1 comprises a table-like frame I0 uponwhich an axle II for the work clamp I2 is rotatably supported in endframes I3 mounted thereon. This axle is driven through a geartransmissionenclosed Within a hood M mounted on these end frames I3.This gear transmission is driven by a motor I5 which is connectedthereto through a speed reducer I6. Motor I5 and speed reducer I6 aremounted on frame I0. Also mounted on frame I0 is a support I'I forpositioning the welding agency I8 relative to a jig I9 which lspositioned between the clamping members 20 of the work clamp I2. Thisjig holds the work in assembled positionY for welding and is locatedbetween clamping-l members 20 of the work clamp I2. 'Ihe welding agencyillustrated is an automatic atomic hydrogen welding head havingsubstantially the'same construction as that illustrated and describedin. my United States Letters Patent 1,946,305 granted February 6, 1934.

The construction of the work clamp I2 and jig I9 as well as the assemblyof the work parts in the jig will become apparent from a considerationof Figs. 2 to 6, inclusive.

The work clamp as shown in Figs. 2, 3 and 4, comprises a body portion 2|connected through spokes 22 to a hub 23 which is mounted on and keyed toone end of axle il. Forming an integral part of the body portion 2i ofthe clamp are two cylinders 24 of a fluid operated mechanism for itsclamping members 20. These clamp ing members are segmental in shape andoffset from the body portion of the clamp by being mounted on pins 25which are bolted to the -body portion of the clamp. The outer clampingmember 20 is stationary, being bolted against a shouldered portion atthe outer end of each of the pins 25. ported on the middle portions ofthese pins 23 and slidably mounted thereon through bushings 28. Theinner face of the inner clamping member is connected through piston rods21 to the pistons in cylinders 24. Stops 28 which limit* the travel ofinner clamping member 20 toward the body portion 2i of the work clampserve to connect piston rods 21 to this clamping mem# ber. As shown-lnthe drawings, the clamping members 20 are provided with passageways 29for the circulation'fof cooling fluid therethrough.V These passagewaysare series connected through a conduit system which will be describedbelow.

Jig I3, located in Figs'. 2, 3 and 4 between the clamping members 20,has the construction illus trated in these figures as well as in Figs.and 6. It comprises, as best shown in Fig. 6. two segmental plates lliand a mandrel 4I. This mandrelV is also shown in Fig. 5. The twostampings 32, which when welded together constitute theV Vmagazine case,are positionedV on mandrel 3i bers 20 to position the iig relativethereto. The Y opening movement of clamping members 20 is limited ibystops 29 so that the jig is limited in its passage therebetween by theiianged portions of the outer jaws 33 which extend beyond the outsidesurfaces of Jig plates 30.

' The segmental jig plates are positioned relatively to one another bydowels 34 (Fig. 2) located at their inner end portions, and the jigplates are fastened together by a locking pin 35 (Fig. 4) which passesthrough an opening 38 in mandrel 3|. One end of locking pin 35 isrotatably supported in one of the jig plates and its other end isprovidedwith a configuration which latches The inner clamping member 20is sup- Y its ends. In the construction illustrated, this progressiveconvergence of the jaws is obtained through the use oi inserts 39preferably of a material having a greater heat conductivity than the jigplates. It is obvious however that other arrangements may be made toaccomplish the same result. In the arrangement illustrated, the jigplates are made of steel and the inserts of copper which has a high heatconductivity. The result desired is that the work clamp through Workengaging members conduct heat away` from the seam at a substantiallyuniform rate throughout the length of the seam except at its ends wherethe conduction of lhea.t.-fro'm the seam is progressively increased soas to'taper off weld -l penetration at the ends of the seam. Thistaperwith 'a similar configuration in the other jig plate. Mandrel 3|may be provided with spring pressed bosses 31 winch extend from thesurface of mandrel 3i into engagement with the stampingsof theY magazinecase in order to exert a pressure through them on the Jig plates andthus tension the latching mechanism including pin 35. Lugs 38 attachedtothe ends of iig plates 3B also serve to hold and position the inturnedportions of the discharge end of the magazine cases as shovvm in Figs. 5and 6. The other ends of these cases are open thus permitting the weldedassembly to .be withdrawn ,from each end of mandrel 3i.

Y .As best shownin Figs. 3 and 6. clamping jaws 33 jig plates Miprogressively' converge toward one another at each end of a seam to bewelded to increase conduction' of heat the seam at ing oi of weldpenetration at the ends of the seam prevents notch-back which wouldoccur if the same pool of molten metal were obtained at the ends of theweld as is obtained during welding its center portions. The notch-backresults from such pool of molten metal forming a ball short oi' the endsof the seam by the withdrawal of molten metal from the ends of the seamprobably due to a Vsurface tension effect.

The jaw construction of the inner and outer edges of the jig plates issubstantially uniform and these jaws are substantially uniformly spacedfrom Vopposite sides of the seam except at its ends where, theyprogressively converge toward one another and the seam to increaseconduction ofrheat from the seam and thereby reduce weld penetration andprevent notch-back. It is to be noted that the welding agency which hasa. 4substantially constant output is traversed relatively to the seamvat a substantially uniform rate of speed and at a substantially uniformspacing therefrom. The heat output of the welding agency is notcontrolled at the end of the seam in order to control weld penetration.This weld penetration is regulated by controlling the amount of heatextracted from the seam through the agency of jaws forming part of thework clamp.

The welding agency I8 is positioned in the plane of rotation of theconcentric arcuate seams in the magazine cases by a support i1. Theconstruction of this support is shown in Figs. 7, 8 and 9. The weldingagency is attached to a bracket 40' which is attached by bolts 4i to theupper end of a piston 42 whose lower end is enclosed by a cylinder 43.The upper portion of piston 42 engages bearings 44 located in the'endportions of a guiding cylinder 45. Cylinders 43 and 45 are attached tothe top surfacel of frame l0 of the welding machine.

Also attached to bracket 40 is a cylinder 4B which encloses a piston 41mounted on a hollow piston rod 4B. As shown in Fig. "I, the lowerwelding position of bracket 40, and of the welding agency supportedthereon, is determined by the engagement of the lower end of hollowpiston rod 48 with shoulder 49 of a rod 50 which extends lengthwisethrough the hollow piston rod 48, piston 42, and the lower end of`cylinder 43. If iluid at the same pressure is admitted to cyl inders 43and 46 through passageways 5l and 52, piston 42 will move Yupwardlythrough cylinder 43 until piston rod 48 engages a nut B3 at the upperend of rod 50. This will locate the welding agency supportedV on bracket40 in its upper welding position. Piston rod 48 will not move relativeto its cylinder 4G since piston 4l is held in the upper portion oi itscylinder by fluid admitted through passage 52. It is to be y 2,358,144vnoted that the area of piston 41 is much greater than the area ofpiston 42 and consequently fluid at the same pressure admitted tocylinders 43 and 46 will cause movement of piston 42 in cylinder 43 butwill prohibit movement of piston 41 in cylinder 46.

If it is desirable to move bracket 40 and consequently the weldingagency still further away from the Work clamp to facilitate loading orunloading operations. this may be accomplished by admitting fluid underpressure through a passage 54 to the upper portion of cylinder 46 andexhausting fluid through passageway 52 from the lower portion ofcylinder 46 while maintaining the fluid pressure connection withcylinder 43 through its passageway 5|. This will cause cylinder 46 andconsequently bracket 40, to travel upwardly until piston 41 engages thebottom end portion of cylinder 46. `Cylinder 46 and piston 41consequently formpart of a means for moving the supporting bracket 40and consequently the welding agency to a loading and unloading DOsitionbeyond the position determined by nut 53 on rod 50. Nut 53 and shoulder4'9 on rod 50 constitute stops which position the welding agencysupported on bracket 40 in either of two welding positions. Bracket 40and the welding agency mounted thereon are moved from one weldingposition to the other welding position determined by these stops throughthe agency of meansincludng piston 42 and cylinder 43.

The welding positions may be adjusted by adjusting the positions ofstops 49 and 53. This may be done by moving rod 5I) relatively to frameI simultaneously to adjust both welding positions and by adjusting theposition of nut 53 on rod 50 to adjust one welding position relative tothe other. As shown in Fig. 1, rod 50 is connected to one end of a lever55 whose other end is connected to a rod 56 which is adjustable relativeto the machine frame I0 by a cam operated through the agency of a handwheel 51. The mid-portion of lever 55 is pivotally supported at thelower end of a rod 58 whose upper end is attached to machine frame I0.

Means are also provided for swinging bracket 40 about the longitudinalaxis of rod 50 so that the welding agency may be adjusted transverselyto the line of welding. This adjustment is provided through a mechanismterminating in a hand wheel 59 (Fig. l). This hand wheel rotates a crankpin 60 (Figs. '1 and 8) through a transmission including gear connectedshafts 6I. One of these shafts 6I as shown in Fig. 1 extends along guidecylinder 45 of support I1 and is supported in the frame I0 and flange 62attached to one another. `As shown in Fig. 11, this cooling iiuid issupplied through a valve 10 which is connected to a source of fluidpressure 1I and to an exhaust passageway 12. Fluid under pressure may-be supplied through valve '10 to A'either of two conduits 13 or 14 whenthe other of these conduits is connected to the exhaust 12.

Conduits 13 and 14 extend through axle II on one end of which work clampI2 is supported. Near the work clamp each of these conduits branchesinto parallel connected conduits which are respectively connected tocylinders 24 and to the cooling passages in clamping members 20. Conduit14 branches into al conduit 15 which is connected to correspondingendsof cylinders 24 and into a conduit I6 whichconnects with one lend ofthe cooling passageway extending through the inner clamping member 20.Conduit 13 branches into a conduit 11 which is connected with thecorresponding opposite ends of cylinders 24 and into a conduit 'I8 whichisconnected through a passage in an outside pin 25 to the correspondingend of the cooling passage in the f cuter clamping member 20. The otherends of the cooling passages in the inner and outer clamping members 20are also connected in series with one another through a conduit 19 and apassageway through an oppositely located outside pin 25. Thepassagewaysthrough which the coolling fluid is supplied to the clamping members 20must either be of such size as to impede the flow of fluid therethroughso as to rbuild up the neces`- sary operating pressure for the fluidcylinders or a restriction may be placed in this cooling passageway foraccomplishing this result.

The physical structure of axle II is shown in Fig. 10. As shown in thisfigure opposite endsl thereof are supported in end frames I3 through theagency of ball bearings; Fluid passages 'I3 40 and 14 are alsoillustrated in these drawings as well as the connection permittingrelative move-- ment between the rotating and stationary por tions ofthese conduits. The coupling between the stationary'and rotatingportions o f these conduits are supported by a bracket 80 which isbolted to one of the end frames I3.

A gear 8| forming part of the transmission between motor I5 and axle IIis shown in Fig. l0. .In this same gure part of a counterbalance 32 forwork clamp I2 is also shown. This counterbalance is fully illustrated inFig. 12. As shown in this figure, it comprises a segmental weight'83 tothe rim of which there is adjustably attached another weight 84. Byshifting the upper portion of cylinder 45. This crank pin is connectedthrough avlink 63 to an arm 64 attached to a collar 65 which isconnected through keys 66 with piston 42. Elongated key ways 61Y inpiston 42 provide for relative lmovement of this piston and collar towhich keys 66 are attached. Collar 65 is held in place on the upper endof cylinder 45 by a cover plate 68 which is attached through spacers 69to flange 62 forming part of the upper end of guide cylinder 45. It isthus apparent that by rotating hand wheel 51, shafts 6I are rotated andin turn rotate collar 65 and piston 42. The rotation of piston 42rotates the support bracket 40 for the welding agency.'

As stated above, cooling iiuid is supplied under pressure to theclamping members 20 of work clamp I2 as well as to opposite ends ofcylinders 24 forming part of the fluid operated mechanism for moving theclamping members 20 relative tcweight 84 relative to weight 83, anadjustment is provided for accurately balancing the work clamp. jig, andwork parts also supported on this -same shaft.

Not shown in any of the drawings are certain control switches which arealso mounted on axle II. These control switches are employed forstarting and stopping the welding agency and form part of the control ofthe welding agency and travel motor I5.

In view of the above description, it is believed that the operation ofmy welding machine is apparent. Briefly stated it is as follows:

Two pairs of complementary punchings, which in assembled relationshipform two magazine cases, are assembled on mandrel 3| and between jigplates 30 as shown in the drawings. This assembly is then insertedbetween clamping meme bers 2li of the work clamp I2 Where it is postioned by the outside flanges of outer jaws 33. engagingcorrespondingedges of clamping mem-I v ',jbers Valve 'l0 is then operated to closethe clampgwhich holds the jig by reaso'nof its configuration properlyvpositioned relative to the welding agency I8.

Either the outside or inside concentric seam is then ywelded by properlypositioning the Welding hagency relatively to the work clamp and jig bypositioning support l'lv through the control of fluid-pressure in..cylinders 43 and 46.` The operation of the welding agency is theninitiated if not already functioning, and feed motor l traversesthe'work assembly jig. and `clamping members vat a substantially uniformrate of speed past the welding agency. This agency is` supported at asubstantially uniform distance from the seam to be welded throughout acomplete welding operation,

After one of the concentricarcuate seams has beenfwelded, the weldingagency is then positioned for welding the other seam. Interferencebetween the welding agency and the work clamp is prevented by thecontrol switches above mentioned which are mounted on the axle of thework clamp. These control switches may also ac'tuate valves to controlfluid pressure in cylinders 43 and 46 to provide a fully automaticoperation of the welding machine. With such operation, the welding headwould be lowered from its loading position into a position for weldingone of the seams and after welding this seam would automatically betransferred to a position for welding the other seam which would then bewelded. After both seams had been Welded, the welding head would againbe moved to its loading position. The jig and welded assembly are thenremoved from work clamp l2. The Welded cases are then removed from thejig by opening jig plates 30 and withdrawing them from mandrel 3l.

To facilitate speed in welding, a plurality of jigs and mandrels may beprovided so that loading and unloading operations thereof may beperformed by the welding operator while the welding machine isperforming a welding operation.

It is of course apparent that many variations may be made in theconstruction and arrange- I ment of parts of a welding machine embodyingmy invention. It will, of course, be necessary to change theconfiguration and shape of the jig and work clamp to accommodate variouswork assemblies providing inner and outer concentric arcuate seams to bewelded. The work holding arrangement when constructed to perform mymethod of welding, will always operate to conduct heat from the seam ata substantially uniform rate except at its ends where heat will beconducted from the seam in progressively increasing amounts suiiicientto taper off Weld penetration at the ends of the seam and thus preventnotch-back due to the action of the welding agency, Such an arrangementmakes it unnecessary tovcontrol the heat supplied by the welding agencyat the ends of the seam, as has been previously proposed.

It is to be understood that the machine above illustrated andndescribedis but one embodiment of my invention and of the principles thereofinvolved. I therefore aim in the appended claims to cover allmodifications of my invention which fall within the true spirit andscope thereof.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. Welding apparatus comprising a welding agency' of substantiallyYconstant heat output, a work clamp having heat conducting jaw memberswhich are spaced from one another and engage the work in said clamp onopposite sides of the seam to be welded, and means for traversing saidwelding agency and said wgrk clamp relatively to one anotheralong saidseam 'and across its ends at a substantially uniform rate of speed withsaid welding agency spaced a substantially uniform distancefrom saidseam, said jaw members of said work clamp being formed at their ends andat the ends of said seam of a material having a greater heatconductivity than the material of which they are formed intermediatetheir ends and the ends of said seam, the relative spacing and heatconductivities of said jaw members being such as t'o increase theconduc-v .-,the heat supplied thereto by traversing said welding agencyalong said seam and across its ends.

2. Welding apparatus comprising a welding agency of substantiallyconstant heat output, a work clamp having heat conducting jaw memberswhich are spaced from one another and engage the work in said clamp onopposite sides of the seam to be welded, and means for traversing saidwelding agency and said work clamp relatively to one another along saidseam and across its ends at a substantially uniform rate of speed withsaid welding agency spaced a substantially uniform distance from saidseam, said jaw members of said work clamp being substantially uniformlyspaced from opposite sides of said seam except at its ends where theyprogressively converge toward one another and said seam at their endsand the ends of said seam to increase conduction of heat from said seamand thereby reduce weld penetration and prevent notching of said work atthe ends of said seam due to the heat supplied by traversing saidWelding agency along said seam and across its ends.

'3. Welding apparatus comprising a segmental clamp, means offset fromone side of said clamp for rotating it in a plane about an axis ofrotation, means for positioning inner and outer concentric arcuateseams'of a work assembly in said clamp with their common center in saidaxis of rotation of said clamp, said means having jaw members which haveend portions of a material whose heat conductivity is greater than thatof the material between said end portions and which when in engagementwith said work assembly are substantially equally spaced from oppositesides of said inner and outer concentric arcuate seams except at theirends where they progressively converge toward one another and the endsof said seams, a welding head, means for supporting said welding headopposite said seams in said plane of rotation of said clamp, and meansfor moving said welding head and said clamp relatively to one another insaid plane of rotation of said clamp from a welding position spaced fromsaid axis of l erated means and to said cooling passages, said coolingpassages restricting the ow of fluid, therethrough suiliciently to buildup a, desired uid operating pressure in said uid operated means, andmeans for transver'sing said weldingv agency and said work clamprelatively to one another.

5. Welding apparatus comprising an axle, means for supporting androtating said-axle about its longitudinal axis, a segmental clamp havingrelatively movable clamping members, means o'set from one end of saidaxle for supporting said clamp for rotation in a plane about the axis ofrotation of said axle, fluid operated means for moving onepf saidclamping members relatively to the other of said clamping members, iiuidcooling passages in said clamping members, means for supplying fluidunder pressure through passageways in said axle and through parallelconnected passageways to said uid operatedmeans and to said coolingpassages, said cooling passages restricting the flow of fluidtherethrough sulicien'tly to buildup a desired iiuid operating pressurein said fluid operated means, means for positioning inner and outerconcentric arcuate seams of a work assembly in said clamp with theircommon center in the axis of rotation of said axle, a welding head,means for supporting said welding head opposite said seams in said planeof rotation of said clamp, and means for moving said Welding headrelatively to said clamp from a welding position suitable for weldingone o f said concentric arcuate seams to a welding .position suitablefor Welding the other of said concentric arcuate seams.

6. Welding apparatus comprising a segmental clamp, means oiset from oneside of said clamp for rotating it in a plane about 'an axis ofrotation, means for positioning inner and outer concentric arcuate seamsof a work assembly in said clamp along opposite sides thereof with theircommon center in said axis of rotation of said clamp, a welding head,means for supporting said welding head opposite said seams in said plane.of rotation of said clamp, and means for moving said welding head andsaid clamp relatively to one another in said plane of rotation of saidclamp from a Welding position spaced from said axis of rotation of saidclamp a distance suitable for welding one of said concentric arcuateseams 'to a Welding position spaced from said axis of rotation of saidclamp a distance suitable for welding the other of said concentricarcuate seams.

7. 4Welding apparatus comprising a segmental clamp, 'means offset fromone side of said clamp for rotating it in a plane about an axis ofrotation, means for positioning inner and outer concentric arcuate seamsof a work assembly in said clamp along opposite sides thereof with theircommon center in said axis of rotation of said clamp, means for rotatingsaid clamp about said axis of rotation, a welding head, meansforsupporting said welding head in said plane of rotation of said clamp,means for moving said welding head and said clamp relatively to oneanother in said plane of rotation of said clamp from a welding positionspaced from said axis of rotation of said clamp a distance suitable forwelding one of said concentric arcuate seams to a welding positionspaced from said axis of rotation of said clamp a distance suitable forwelding the other of said concentric arcuate seams, and additional meansfor moving said welding head and said clamp relatively to one another insaid plane of rotation of said clamp away from said axis of rotation ofsaid clamp a sulcient distance'from` tions said welding agency in saidplane of rotation of said clamp for travel toward and away from saidaxis of rotation of said clamp, a plurality of stops located in the pathof travel of said support and acting thereon when said welding agency isin welding positions for said inner and outer concentric seams' ofthework supportedin saidclamp, means including a piston and cylinder formoving said support from the position vdetermined by one of said stopsto the position determinediby the other of said stops, and meansincluding a second piston and cylinder for moving said support beyondthe position determined by one of said stops. y

9. Welding apparatus comprising a segmental clamp, means oiset from oneside of said clamp for rotating itin a planel about an axis of rotation,means for positioning inner and outer concentric arcuate seams of a Workassembly in said clamp alongopposite sides thereofwith their commoncenter in said axis of rotation of said clamp, means for rotating saidclamp about said axis of rotation, a welding agency, a support whichpositions said welding agency in said plane of rotation of said'clampfor vtravelk toward and away from said YKaxis of rotation of saidclamp,a plurality of stops locatedfin the path of travel of said support'andacting thereon when saidwelding agency is in welding positions for saidinner and outer concentric seams of the Work supported in said clamp,means for adjusting said stops in the direction of travel of saidsupport relative thereto, means including a piston and cylinder formoving said support from the positionl determined by one of said stopsto the position determined ,by the other of said stops, and meansyincluding a second piston and cylinder for moving said support beyondthe position determined by one of said stops.

10. Welding apparatus comprising a segmental clamp,'means offset fromone side of said clamp for' rotating it in a plane'about an axis ofrotation, means for positioning inner and outer concentric arcuate seamsof a work assembly in said clamp along opposite sides thereof with theircommon center in said axis of rotation of said clamp, means for rotatingsaid clamp about said axis of rotation, a welding agency, al supportwhich positions said welding agency in said plane of rotation of saidclamp for travel toward and away from said axis of rotation of saidclamp, a

plurality of stops located in the path of travel of said support andacting thereon when said welding agency is in welding positions for saidinner and outer concentric seams of the Work supported in said clamp,means for adjusting said stops in the direction of travel of saidsupport relative thereto, means including a piston and cylinder formoving said support from the position determined by oneof said stops tothe position determined by the other of said stops, means including asecond piston and cylinder for moving said support beyond the positiondetermined by one of said stops, and means for rotating said support andthereby adjusting saidl welding agency transversely of the seam beingwelded.

11. Welding apparatus comprising an. axle, means for supporting saidaxle for rotation about its longitudinal axis, means for rotatingsaidaxle about its longitudinal axis, a segmental clamp having relativelymovable clamping members oiset from one side of said axle, means formoving one of said clamping members relatively to the other of saidclamping members, means for positioning inner and outer concentricarcuate seams of a work assembly in -said clamp with their common centerin the axis of rotation of said axle, a welding agency, a support whichpositions said welding agency for relative travel along said Vconcentricarcuate seams of said workassembly in said clamp, means including apiston and cylinder for moving said support toward and away from saidclamp to position said welding agency for welding one or the other ofsaid con- -centric arcuate seams of said work assembly in said clamp, asecond piston and cylinder one elementV of which is attached tosaidsupport and the other element of which is movable relativelythereto,said second ,piston and cylinder having a piston area greaterthanthie piston area of said first mentioned piston and cylinder, a stopat each end of and in the path of travel of said other element of saidsecond piston and cylinder, and means for lsupplying pressure iluid toone end of said first mentioned cylinder and to opposite ends of saidsecond mentioned cylinder to locate said welding agency in weldingpositions for one or the other oi said concentric arcuate seams of thework assembly in said clamp and in a loading and unloading positionspaced from one of said welding positions by a predetermined distanceequal to the stroke of said second mentioned piston and cylinder. L

12. Welding apparatus comprising an axle,

means for supporting said axle for rotation about its longitudinal axis,means for rotating said axle about its longitudinal axis, a segmentalclamp having relatively movable clamping members offset from one end ofsaid axle, uid operated means in said clamp for moving one of saidclamping members relatively to the other of said clamping members, fluidcooling passages in said clamping members, means for supplying uid underpressure through passageways in said axle and through parallel connectedpassageways to said fluid operated means and to said cooling passages,said cooling passages restricting the flow of fluid therethroughsufficiently to build up a desired iiuid operating pressure in saidfluid operated means, means for positioning inner and outer concentricarcuate seams of a work assembly in said clamp with their common centerin the axis of rotation of said axle, said means having jaw memberswhich make a heat conductive entially equally spaced from each other andsaid"y seams except at the ends of said seams where they progressivelyconverge toward one another and said seams to increase conduction ofheat therefrom, a welding agency, a support therefor, a plurality ofstops for locating said support in welding positions for said inner andouter concentric seams of the work supported in said clamp, means foradjusting said stops in the direction of travel of said support relativethereto, means including a piston and cylinder for moving said supportfrom the position determined by one of said stops to the positiondetermined by the other of said stops, means including a second pistonand cylinder for moving said support beyond the position determined byone of said stops, and means for rotating said support to adjust saidwelding agency transversely of the seam being welded.

JAIWES T. CATLET'I'.

